linux-kernel - Re: [PATCH v10 0/4] Add support for AArch64 AMUv1-based average freq

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Message-ID: <Z7PNlFv2995pDARQ@arm.com>
Date: Tue, 18 Feb 2025 01:00:20 +0100
From: Beata Michalska <beata.michalska@....com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org, ionela.voinescu@....com,
	sudeep.holla@....com, will@...nel.org, rafael@...nel.org,
	viresh.kumar@...aro.org, sumitg@...dia.com,
	yang@...amperecomputing.com, vanshikonda@...amperecomputing.com,
	lihuisong@...wei.com, zhanjie9@...ilicon.com,
	ptsm@...ux.microsoft.com, Jonathan Corbet <corbet@....net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H . Peter Anvin" <hpa@...or.com>, Phil Auld <pauld@...hat.com>,
	x86@...nel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v10 0/4] Add support for AArch64 AMUv1-based average freq

On Mon, Feb 17, 2025 at 09:32:06PM +0000, Catalin Marinas wrote:
> On Fri, 31 Jan 2025 16:24:35 +0000, Beata Michalska wrote:
> > This series adds support for obtaining an average CPU frequency based on
> > a hardware provided feedback. The average frequency is being exposed via
> > dedicated yet optional cpufreq sysfs attribute - cpuinfo_avg_freq.
> > The architecture specific bits are being provided for AArch64, caching on
> > existing implementation for FIE and AMUv1 support: the frequency scale
> > factor, updated on each sched tick, serving as a base for retrieving
> > the frequency for a given CPU, representing an average frequency
> > reported between the ticks.
> > 
> > [...]
>
Thank you for that.

There is still a (not so) small issue with patch
[3/4] arm64: Provide an AMU-based version of arch_freq_get_on_cpu.
It did not come up while testing, sadly.
No idea how I could have missed that, nor why I made the mistake
in the first place.

The fix is pretty straightforward:

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 6f0cab8e746b..4bac26d8e29c 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -268,7 +268,7 @@ int arch_freq_get_on_cpu(int cpu)
 
                        do {
                                ref_cpu = cpumask_next_wrap(ref_cpu, policy->cpus,
-                                                           start_cpu, false);
+                                                           start_cpu, true);

Please let me know if you want me to send new version with the fix applied.

Apologies for the inconvenience.

---
BR
Beata

> Applied to arm64 (for-next/amuv1-avg-freq), thanks!
> 
> [1/4] cpufreq: Allow arch_freq_get_on_cpu to return an error
>       https://git.kernel.org/arm64/c/38e480d4fcac
> [2/4] cpufreq: Introduce an optional cpuinfo_avg_freq sysfs entry
>       https://git.kernel.org/arm64/c/fbb4a4759b54
> [3/4] arm64: Provide an AMU-based version of arch_freq_get_on_cpu
>       https://git.kernel.org/arm64/c/dd871ac1237f
> [4/4] arm64: Update AMU-based freq scale factor on entering idle
>       https://git.kernel.org/arm64/c/96b335620c59
> 
> -- 
> Catalin
>